1. Field
Embodiments of the inventive concept relate to an electronic circuit, and more particularly, to an oscillator to generate a clock signal and a device including the same.
2. Description of the Related Art
A ring oscillator is usually used to generate a reference clock signal. In order to minimize a frequency change with respect to a temperature change, a temperature-compensated current which is the same as a current generated in a band gap reference (BGR) circuit is usually used in a ring oscillator design. However, a circuit for generating the temperature-compensated current usually includes a single operational amplifier and a plurality of resistors, and therefore, it is hard to be implemented in a design for an ultra-low current (e.g., nano-current) operation such as a standby mode (or a stop mode).
An ultra-low current reference clock generator requires a stable frequency characteristic with respect to temperature change and a minimum operation current as well. However, it is hard to satisfy these requirements with a conventional design method that requires several resistance elements with a resistance ranging from several MΩ to several tens of MΩ.